Apparatus for the production of artificial silk and the like



June 9, 1925.

J. F. BRIGGS ET AL APPARATUS FOR THE PRODUCTION OF ARTIFICIAL SILK ANDTHE LIKE Filed May 14, 1923 3 Sheets-Sheet 1 mm QM g w INVENTORS:

JOHN F. BRIGGS, WILFRED YORKE,

By their Attorneys,

June 9, 1925. 1,541,104

J. F. BRIGGS ET AL.

APPARATUSFOR THE PRODUCTION OF ARTIFICIAL SILK AND THE LIKE Filed May14, 1923 5 Sheets-Sheet 2 INVENTORS:

JGHN F'. BRIGGS, WILFRED YORKE, By their Attorneys,

June 9, 1925. 1,541,104

.1. F. BRIGGS ET AL v APPARATUS FOR THE PRODUCTION OF ARTIFICIAL SILKAND THE LIKE Filed May 14, 1925 3 Sheets-ZSheet 5 zj 17 3Q INVENTORS:

JOHN F. BRIGGS: WILFRED YORKE, By their Attorneys,

' that any desired number of Patented June 9, 1925.

UNITED STATES 541,104 PATENT OFFICE.

JOHN FREDERICK BRIGGS AND WILFRED COMPANY, LIMITED, OF NEW YORK, N.

YORKE, OF SPONDON, NEAR DERBY, ENG- LAND, ASSIGNORS TO AMERICANCELLULOSE AND CHEMICAL MANUFACTURING Y., A CORPORATION OF DELAWARE.

"APPARATUS FOR THE PRODUCTION OF ARTIFICIAL SILK AND THE'LIKE.

Application filed May 14,

To all whom it may concern:

Be it known that we, JOHN FREDERICK Braces and WILFRED Yomm, subjects ofthe King of Great Britain. and residents of Spondon, near Derby,England, have invented certain new alnd useful Improvements Relating toApparatus for the Production of Artificial Silk and the like, of whichthe following is a specification.

This invention relates to apparatus for the production of artificialsilk and like threads or filaments from solutions of cellulose acetates,nitro cellulose, cellulose others, or other cellulose derivatives by theevaporative or dry spinning method, wherein a solution of the cellulosederivative in or containing vaporizable solvent is discharged throughjets, nozzles or orifices, into a current of hot or warm air drawn orpassed through the chambers wherein the solution is discharged, thefilaments or threads being solidified by the resulting evaporation ofsolvent therefrom, and the vapor laden air from the chambers being drawnor conveyed away from the chamhers.

This invention applies to apparatus wherein a metier or metiers aredivided up into a number of spinning cells or compartments, hereinafterreferred to as cells each containing a desired small number ofspinnerets. Such apparatus is hereinafter referred to as dry spinningapparatus of the cellular type, it being further understood such metiersor groups of cells may be employed in an installation.

The invention is particularly applicable to apparatus wherein thefilaments or threads are spun downwards into the cells of the metiercasing from the upper partthereof, and travel down through a current ofhot or warm air drawn or passed up through the cells or compartments ofthe metier and out at the upper part to an evacuating pipe or conduit,the filaments or threads of associated filaments being led out of themetier casing and wound up continuously outside the same, as has beenindicated in a previous British'specification No. 165,519, but theinvention may also be applied to other forms of apparatus working on theevaporative method. where the metier casing is divided up into vertical1923. Serial No. 638,904.

cells, each producing a number. of threads or filaments.

In practice it has been found that the quality and uniformity of thefilaments or threads produced in the cells of a metier or set of sellsengaged in spinning any given denier, are liable to be affected by theexistence or occurrence of differences in the splnning conditionsprevailing in the respective cells, that is to say differences asbetween cell and cell and that, in order to obtain filaments or threadsof similar quality and uniformity, of a given required denier, in thedifferent cells it is important that slmilar spinning conditions shallbe maintained in the different cells producing to given denier. Also forspinning different deniers, it is necessary to adapt the spinningconditions in the cells accordingly.

In the following description the invention will be described in itsapplication to a dry spinning metier casing divided up into cells in amanner similar to that described in the said specification 165,519, thehot or warm air being drawn up through the cells and out at the upperpart thereof, it being understood however, that the invention is notrestricted to such an arrangement.

We have found that it is of importance that the volume of vapour-ladenair passing from each cell of a metier or set of cells producing anygiven denier, should correspond as uniformly as possible with thatpassing from its fellows, and that the concentration of thisvapour-laden air for any given denier should be as uniform as possible,that'is to say, the air volume passing through each cell should be undercontrol and proportional to denier. Also the temperature of the airshould be kept as uniform as possible at corresponding points of thedifferent cells.

According to the present invention we provide each cell of a metier orset of cells, with a separate outletor connection to a pipe or conduitconnected to-the exhaust and which serves to carry off the vapour laden.air from the metier or set or series of cells or compartments,hereinafter referred to as the collecting pipe orheader, and we provideeach of said outlet pipes or connections with a valve or device forcontrolling or regulating the flow through same, and

with a flow meter or other device for indicating the volume ofvapour-laden air pass ing from the corresponding cell.

By this means the volume of air passing from each of the cells of themetier or set of cells or compartments can be observed and adjusted asrequired for-any particular denier, and differences which may exist orwhich may arise in working between the volumes passing from therespective'cells in operation can be observed and regulated so as topreserve approximate uniformity between the volumes passing from therespective cells. Also any given compartment or compartments of themetier or set may be cut out by closing their outlet controlling valvesor devices when required, Without stopping the operation of the othercompartments.

In addition to providing the outlet pipe or connection of eachcompartment of the metier or set of cells with indicating andcontrolling devices as explained, we may also provide in connection orcombination with the collecting pipe or header to which they areconnected, a flow meter or other devices for: indicating the volumeflowing through said collecting pipes or header, and a valve or devicefor controlling or adjusting the flow therein. Such control can thusserve for varying the suction or flow in the collecting pipe or headerserving the metier or set of cells, as for example for adjusting thegeneral suction or flow from the metier or set of cells for producingdifferent deniers in themetier or set of cells or for cutting out thesame from operation, the individual controlling valves or devices on theoutlet connections from the cells providing for any further orindividual adjustment which may be necessary.

An installation may comprise one or any desired number of cellular meters or sets .of cells. Usually a number of metiers or sets of cells willbe employed, each metier or set of cells being provided with acollecting pipe, or section of collecting pipe, to which the outletsfrom its cells are connected, each such collecting pipe or section ofcollecting pipe being preferably separate from or capable of beingisolated from the others, and preferably a flow indicating device and aflow controlling device are 'provided in connection with the collectingpipe, or header'or section of collecting pipe, of each metier or set ofcells, in such manner that the flow from any given metier or set ofcells may be adjusted for the production of a different denier to thedevice or deniers which are being produced in other metiers or sets ofcells, or that the given metier or set of cells may be cut out ofoperation.

A general flow indication and control may,

however serve two or other desired number of metiers or sets of cells 1fdesired. The

collecting pipes or sections of collecting pipe of the respectivemetiers or sets or series of compartments may be connected to a com--mon exhaust main or trunk.

Any known or suitable flow meters or devices may be employed forshowingthe volume" of vapour-laden air passing from the-cells, or thevolume passing in the collecting pipe or header or -in the respectivecollecting pipes or sections of collecting pipe as before referred to,and such devices may indicate the volume either directly or indirectly.For example we may employ flow meters in the form of water gauges orflow meters of a type analogous to a Venturi ow meter or a Capok flowmeter, comprising a constricted portion or throat through which the flowpasses and a water gauge serving to indicate or represent the volumeflowing at a given moment.

Further according to the invention we may provide means for regulatingthe temperature in the cells, and preferably we provide each cell withmeans for regulating the temperature therein so that the temperature ineach can be regulated independently. Such means may consist for exampleof a regulating valve provided between the cell and the air supply whichdelivers into it. The air regulating valves may be of screw mushroomtype or any other suitable form. Usually the hot air rises through thecells from an air heater consisting of steam heated pipes situated inthe lower part of the metier or set of cells, and extending through orunder the cells thereof.

Auxiliary heating means may if desired be provided in the cells forfurther heating the air rising through same. Such means may consist forexample of steam heated pipes extending through the metier or set ofcells at a part near or towards the end of the path of the filamentstherein and extending for any desired distance above this point.

Further according to the invention we may employ, in combination withthe metiers or sets of cells provided with How measuring and flowregulating arrangements as referred to, dchumidifying and preliminaryheating apparatus serving for dehumidifying the air to be supplied tothe inetiers or sets of cells or compartments by cooling it to a lowtemperature in order to deposit moisture therefroi'n, and for heatingthe thus dried air to a desired temperature before it passes to the airheating apparatus proper combined or associated with the. metiers orsets of cells.

Any suitable apparatus may be employed for this purpose. According tothe preferred form such apparatus may comprise two brine cooled aircoolers arranged to be connected alternately to a preheater. and eachbeing adapted to be connected to the warm air discharge side of thepreheater or other Ill) suitable source of heat, valves or controllingdevices being provided, so that when one air cooler is in operation andconnected to the inlet side of the preheater, the other can be shut offfrom the inlet side of the nreheater and connected to the discharge sidethereof or other source of heat, in order to thaw up, the air coolerwhich has been cut out of operation.

To illustrate how the invention may be carried. out, we will describeone arrange ment of apparatus constructed in accordance therewith, itbeing understood that this is given only by way of example and can bevaried considerably without departing from the invention. In thisapparatus any desired number of metiers are employed of a type similarto that described in the said specification No. 165,519, that is t0 saythe metier is divided up into cells wlth the ets or spinnerets situatedin the upper part of the cells, the threads or filaments beingspundownwards through an upward current of hot air in the cells and beingled out at the lower part of the cells and wound up outside the metiercasing.

The accompanying drawings illustrate diagrammatically as much of anapparatus accord ng to the invention as is necessary to enable theinvention to be understood, ten cells of a metier bein shown.

Fig. l'is a general diagrammatic elevation of the apparatus with themetier casing in section.

Fig. 2 is a diagrammatic rear elevation of a ten-cell length or portionof metier looking towards the right of Fig. l, the rear wall of themetier casing of four of the cells being broken away.

Fig. 3 is a plan of Fig. 2.

Fig. is a diagrammatic front elevation of the said length or portion ofmetier, and Fig. 5 is av diagrammatic plan in horizontal section on line55 of Figure 4 through the top of the metier cells.

The enclosed metier casing A, Fig. 1 is divided up into vertical cells 1as before mentioned and may comprise any desired number of such cells, 2are spinnerets fitted in the top of the cells 1' and supplied withspinning solution through valved pipes 3 from solution piping 3, 3, bysmall pumps, similarly to the apparatus of the said specification165,519. one of the pumps being indicated at 4, Fig. 1. In the drawings,there are two spinnerets per cell, but a number other than two might beemployed per cell, even only one spinneret per cell. The filaments 5,spun downwards through the cells 1. are associated into threads 6 andpass out through small openings 7 (Figs. 1 and .3) in the front of themetier "casing and are fed by a line of godet rollers 8 to bobbins orwinding up devices 9. all as explained in the said specification165,519. 1* indicates the W111- dows in each cell at the top of themetier casing, for inspection and access to the spin.- nerets, and.1indicates similar windows at the bottom of the metier casing forinspection and access.

Each cell 1 is fitted at the upper end with an outlet pipe 10, of smalldiameter, e.- g., inch, connected to a collecting air suction pipe orheader 11 of larger diameter, 0. g., 3 inches, which extends all alongthe metier. The ipes 10 can thus take the vapour-laden air rom upperpart of the metier cells. Each outlet pipe 10 outside its cell isconnected to a tube 12 which dips into a water trough 13 runningthelength of the metier and constitutes a Water gauge forming a flowmeter which represents, by the level of the liquid in the tube, thevolume of air flowing from that particular cell at any moment. Aregulating valve 14 (Fig. 1) of any known or suitable kind is likewiseprovidedin each outlet pipe 10, so that the flow of vapour laden airfrom each cell can be regulated, according to requirement, or beentirelv cut ofi', as before explained. a The said regulating valves areshown as operated by screw rods 15 extending down to a convenientposition and provided with hand wheels 16. Thus the flow from each, cellof the metier can be independently regulated to maintain approximateuniformity between the volumes passing from the respective cells of themetier.

The collecting air suction pipe or header 11 is coimected through abranch 17 to a main exhaust pipe 18 leading to a fan or exhauster 19which can deliverthe vapour laden air to solvent recovery apparatus inthe known way. In the branch 17 is fitted a throat or constrictedportion 20 which is connected to one limb of a U-tube 21, the other limbof which is connected to the por tion of the branch 18 preceding thethroat, so as to form a flow meter and show the volume flowing from thecollecting pipe or header 11 of the metier. A regulating valve 22 isalso fitted beyond the throat 20in the branch l'f, so that the flow fromthe metier can be observed and controlled.

The control thus provided by the flow meter 20, 21 and the valve 22 canserve for varying the suction or flow in the collecting pipe or header11 serving all the cells of the metier or set of cells, as for examplefor adjusting the general suction or flow from the metier or setof cellsfor producing different deniers in the metier or set of cells, or forcutting out the metier or set of cells from operation, the individualcontrolling valves 14cm the outlet pipes 10 from the cells providing.for any further or individual adjustment that may be necessary.

23,1'epresents a number of steam pipes passing through the cells of themetier at bottom and forming a heater for heating the travel in themetier and for a desired height 'admission to the cell to be adjusted asdesired, with a view to regulating the temperature of the cells andmaintaining the temperature as uniform as possible at correspondingpoints of the cells of the metier.

The nietier'is shown provided with auxiliary heating means consisting ofhorizontalsteam heating pipes 28 passing through the metier cells andlying behind the path of the filaments near the lower portion of theirabove this point.

The air trunk 24 from which the air passes to the bottom of each cell atthe part where the heater formed by the pipes 23 is situated, issupplied with air from the main 25 to which it is delivered fromdehumiditying and preheating apparatus comprising two brine-cooled aircoolers 29, 29 combined with a preheater 30 for the dried air. The twocoolers 29, 29 have each an air inlet marked respectively 31, 31controlled by a valve marked respectively 32, 32, and are cooled in theknown way by brine, the inlet and outlet connections of which are marked33, 33, 34, 34* respectively in. Fig. 1. The cooling brine supply to theair coolers 29, 29 can be cut in and out by valves not shown. W, V arethe inspection windows of the air coolers. The air coolers 29, 29 areconnected in U-fashion to the pre heater 30 by wide ducts 35, 35 at thejunction of which a pivoted damper 36 is fitted which permits the aircoolers 29, 29 to be connected to the preheater 30 in alternation. onebeing connected while the other is cut out. The preheater is heated by asteam coil. steam jacket or the like, the steam inlet and steam outletbeing indicated at 37, 38, and from the delivery end of the preheater30. air pipes 39, 39 are connected one to each cooler 29, 29, valves 40,40 being fitted in these pipes to open and close the connuunication withthe, coolers. The preheater 30 is connected at the discharge side to theair main 25 leading tothe trunk 24 at the back of the metier, and athermostatic valve indicated at 41 may be provided at the air dischargeside of the preheater 30. A moisture and temperature indicator of thewell known kind comprising a thermometer and a hygrometer may be fittedas indicated at 42, 43 at both the intake and discharge side of thepreheater 30 to observe the moisture and temperature conditions of theair entering and leaving the same.

By suitably manipulating the damper 36and valves 40, 40, the air can bedrawn through one of the coolers 29 or 29 and the preheater 30 so as todry it by deposition of moisture in the cooler and to raise it to adesired temperature before it passes on to the metier under the suctionof the exhauster 19, and when it is desired to thaw up the cooler thedamper 36 can be put over to cut this cooler out and connect the othercoolerto the preheater 30. Warm air can then be turned on to the firstcooler from the discharge side of the preheater 30 in order to thaw itup while the other cooler is in operation.

Any desired number of inetiers constructed and fitted as described maybe employed and'\ may be arranged in a row or rows or be otherwisegrouped according to requirement, each having its cells individuallyconnected to acollectingpipe or header such as ll by' outlet pipes suchas 10, each connected or combined with a flow indicating device andcontrolling valve as explained, and the collecting pipe or header ofeach metier being connected to the main exhaust pipe 18 leading to theexhauster. The collecting pipes or headers of the respective metiers maybe separate from each other or may be connected together, but preferablythey'are separate or capable of being isolated from each other by valvesor otherwise.

The collecting pipes or headers of the re spective metiers will be eachconnected to the main exhaust air pipe 18 through a corresponding pipeor branch provided, similarly to the branch 17, with a flow meter (suchas 20, 21) and a regulating valve (such as 22). Thus the flow from eachmetier can be observed and controlled, in addition to the individualobservation and control provided for the cells of the metier, and anygiven metier can be adjusted for producing a different denier to anotheror others, or can be cut out of operation as required.

The throats or constrictions of the flow meters may if desired be madeof glass or other transparent material so that if any choking shouldoccur this can be readily seen.

It will be understood that wherea number of metiers are employed, theair from the dehumidifying and preheating apparatus can be distributedfrom the air main 25 from this apparatus to the air trunk (24) of eachmetier.

We do not confine ourselves to the employment of a number of metiers orsets of cells, as it will be evident that a single metier or apparatuscomprising any desired number of cells may be employed provided withmeans for indicating and con trolling the flow of vapour-laden air fromthe individual compartments.

Ill)

It will also be understood that the in-.

vention may be applied in connection with other forms of a paratus forproducing artificial silk and t 1e like by the dry spinning or eva)orative method.

What I c aim and desire to secure by Let ters' Patent is 1.-'In dryspinning ap aratus of the cellular ty e for the manu acture ofartificial.

silk an the like, a dry-spinnin -metier comprising numerous spinningcells, a collecting conduit for carrying of! vapourladen air from thecells of the metier to the exhaust, an' individual outletconneccomprising numerous spinning cells, spin nerets disposed in theupper part ofthe cells and arranged to deliver the filaments downwardsthrough same, means for supplying heated air up through the cells fromthe lower part thereof, a collecting conduit for earrying voffvapour-laden am from upper part of the cells of the metier to theexhaust, an individual outlet connection between the up er part of eachof said cells and said col ecting conduit, an indicating device inconnection with each of said outlet connections for individuallyindicating the volume of vapour-laden air passing therein from thecorresponding cell, and a control-r ling device to each outletconnection for regulating and cutting off the flow from thecorresponding cell.

3. In dr spinning ap aratus of the cellular type or the manu acture ofartificial silk and the like, a dry spinning metier comprising numerousspinning cells, a collecting conduit for carrying ofi' vapour-laden airfrom the cells of the metier to the exhaust, an individual outletconnection between each of said cells and said collecting conduit, awater gauge device in connection with said outlet connectionsiorindividually indicating the volume of vapour-laden air passingtherein from the corresponding cell, and a controlling device to eachoutlet connection for regulating and cuttingbfl' the flow from thecorresponding cell.

4. In dry spinning apparatus of the cellular type for the manufacture ofartificial silk and the like, a dry spinning metier comprising numerousspinning cells, a collecting conduit for carrying ofi' vapourladen airfrom the cells ofthe metier to the exhaust, an individual outletconnection between each of said cells and said collecting conduit, anindicating device in connection with each of said outlet connections forindividually indicating the volume of vapourladen air passing therein"from the corresponding cell, a controlling device to each outletconnection for regulatin and cutting off the flow from the correspon ingcell, and devices for indicatin the volume flowing in said collectingcon uit and for regulating and cutting out the flow therein, whereby thei flow from the metier can be adjusted or the metier cut off fromoperation.

5. In drv spinning apparatus of the 061111. lar type for the manu silkand the like, a dry spinning metier comprising numerous spinning cells,a collecting condu1t for carrying ofi vapour laden air from the cells ofthe metier to the exhaust, an 1nd1vidual outlet connection between eachacture of artificial of said cells and said collecting conduit, an

indicating device in connection with each of said outlet connections forindividually indicating the volume of vapour laden air passing thereinfrom the corresponding cell, a controlling device to each outletconnection for regulating and cutting off the flow from thecorresponding cell, aflow indicating device comprising a throat incombination with a water gauge device for indicating the volume flowingin. said collecting conduit, and a valve for .controllin and cutting outthe flow therein, where y the flow from the metier can be adjusted orthe metier cut off from operation.

6. In dry spinning ap aratus of the cellular type for the manu acture ofartificial silk and the like, a dry spinning metier comprising numerousspinning cells, a collecting conduit for carrying off vapour laden airfrom the cells of the metier to the exhaust, an individual outletconnection between each of said cells and said collecting conduit,all-indicating device in connection with each of said outlet connectionsfor individually indicating the volume of vapour laden air passingtherein from the corresponding cell, a controlling device to each outletconnection for regulating and cutting ofi' the flow from thecorresponding cell, and means for indepeiildently regulating thetemperature in each ce 7. In dr spinning .ap aratus of the cellular typeor the manu acture of artificial silk and the like, a dry spinningmetier comprising numerous spinningcells, a collecting conduit forcarrying off vapour laden air from the cells of the metier to theexhaust, an individual outlet connection between each of said cells andsaid collecting conduit, an indicating device in connection with each ofsaid outlet connections for individually indicating the volume of vapourladen air passing therein from the corresponding cell, a

controlling device'to each outlet connection for regulating and cuttingof the flow from the corresponding cell, an air inlet to each cell and avalve device for regulating the amount of air admitted there whereby thetem erature in each cell can be independent regulated.

8. In di" spinning apparatus of the cellular type f or the manufactureof artificial silk and the like, a dry spinning metier comprisingnumerous spinning cells, spinnerets disposed in the upper part of thecells and arranged to deliver the filaments downwards through same, airheatin means situated at the lower part of the cel s, air inlets to therespective cells in the vicinity of said air heating means, a collectingconduit for carrying ofl vapour laden air from the upper part of thecells to the exhaust, an individual outlet connection between the upperpart of each of said cells and said collecting conduit, an indicatingdevice in connection with each of said outlet connections forindividually indicating the volume of va pour laden air passing thereinfrom the corresponding cell, a controlling device to each of said outletconnections for regulating and cutting off the flow from thecorresponding cell, and a valve device'for regulating the amount of airadmitted by each of said air inlets to the respective cells, whereby thetemperature in each cell can be independently regulated.

9. In dry spinning apparatus of the cellular type for the manufacture ofartificial silk and the like, a dry spinning metier comprising numerousspinning cells, a collecting conduit for carrying ofi vapour laden airfrom the cells of the metier to the ex haust, an individual outletconnection between each of said cells and said collecting conduit, anindicating device in connection with each of said outlet connections forindividually indicating the volumeof vapour laden air passing thereinfrom the corresponding cell, a controlling device to each outletconnection for regulating and cutting off the flow from thecorresponding cell, an air inlet to each cell, a valve device forregulating the amount of air admitted there whereby the temperature-ineach cell can be independently regulated, and auxiliary heating meanslocated in the cells and extended from near the end of the path of thefilaments therein for a desired portion of said path.

10. In dry spinning apparatus of the cellular type for the manufactureof artificial silk and the like, a dry spinning metier comprisingnumerous spinning cells, spinnerets disposed in the upper part of thecells and arranged to deliver the filaments downwards through same, airheating means situated at the lower part of the cells, air inlets to therespective cells in the vicinity ecting conduit, an indicating device inconnection with each of said outlet connections for individuallyindicating the volume of vapour laden air passing therein from thecorres onding cell, a controlling device to each 0 said outletconnections for regulating and cutting oil the flow from thecorresponding cell, a valve device for regulating the amount of airadmitted by each of said air inlets to the respective cells, whereby thetemperature in each cell can be independently regulated, and auxiliaryheating means located in the cells and extending from near the end ofthe path of the filaments therein for a desired portion of said path. I

11. In dry spinning apparatus of the cellular type for the manufactureof artificial silk and the like, the combination of plurality ofdry-spinning metiers each comprising numerous spinning cells, acollecting conduit for carrying oil the vapour laden air from its-cellsto the exhaust, an individual outlet connection between each of itscells and the collecting conduit, an indicating device in connectionwith each outlet connection for individually indicating the volume ofvapour laden air passing therein, and a controlling device to eachoutlet connection for regulating and cutting off the flow from thecorresponding cell,-thc collecting conduits of the respective metiersbeing connected to the exhaust and being each provided with devices forindicating the volume flowing in them and with devices for adjusting andcutting out the flow in them respectively, whereby the flow from therespective metiers can be observed and adjusted and cut out of operationas required.

12. In dry spinning apparatus of the cellular type for the manufactureof artificial silk and the like, a dry spinning metier comprisingnumerous spinning cells, a collecting conduit for carrying off vapourladen air from the cells of the metier to the exhaust, an individualoutlet connection between each cell and said collecting conduit, anindicating device in connection with each of said outlet connections forindividually indicatin the volume of vapour laden air passing t ereinfrom the corresponding cell, a controlling device to each outletconnection for regulating and cutting off the flow from thecorresponding cell air supply inlets for the respective cells, an airheater combined in the m;tier, for heating the air supply to the cellsand a dehumidifier and preliminary heater for the air supply, connectedto the air supply inlets of the cells, said de-.

j humidifier and preliminary heater being adapted to deposit moisturefrom the air by cooling and to heat the dried air to a desiredtemperature before it passes to the heater and cells of the metier.

13. In dry s inning apparatus according to claim 12, a ehumidifier andpreliminary heater comprising two brine-cooled air coolers and apreheater, delivery connections between said air coolers and the inletside of said preheater, warm air connections and said air coolers,controlling means for ers to the preheater, whereby the .coolers can be5 alternately connected to the preheater, and controlling devices forsaid warm air connections from the discharge side of the preheater,whereby the discharge side of the preheater can be connected to therespective air coolers alternately for thawing up the same,substantially as described.

In testimony whereof we have hereunto subscribed our names.

JOHN FREDERICK BRIGGS. WILFRED YORKE.

between the discharge side of the preheater I

